This is an ever-growing collection of all my thoughts, strategies and lessons learned while studying storms.
Phase 1: The Potential
Have a purpose:
- Is it serving as media and capturing extreme nature that others don’t often see?
- Is it warning others by providing ground truth and reporting dangerous storms?
- Is it learning the science and growing your skill and intuition as a forecaster?
- Is it being first responder when no one else has responded?
- Is it seeking adventure and craving adrenaline? -Make it all of these
Phase 2: The Pre-Chase
The MCS did go south, didn’t it.
Forget the models; they messed up. Be the model.
Current observations, visible satellite, Mesoanalysis. Subtleties.
Understand the setup:
- Warm front: always
- Triple point: messy but high-impact
- Outflow boundary: easy quick tornadoes, but often unimpressive storms
- Dryline: isolated and powerful or blue sky bust
- Cold-core low: mini-supercells, mini-tornadoes
- Upslope: spectacular, long-lived storms
- Denver Cyclone: highly photogenic tornado or your money back
- Remnant MCV: highly unphotogenic tornado but bragging rights for finding it
- Cold front: last resort
What do you want to see:
- The best ingredients?
- The best tornado potential?
- The best chance of storms?
- The most photogenic storms? -These rarely coincide
Where do you want to go:
- The best terrain?
- The best road network?
- The best cell coverage?
- The farthest from cities?
- The closest to home? -These never coincide
Storms moving at highway speeds allow for an intercept, not a chase.
The best team is made up of people with vastly different definitions of “too close”.
There must be a driver and a navigator/radar operator. The former must trust the latter with his/her life.
There should be at least two different cell data carriers in the group.
A good gut feeling the night before and a feeling of hopelessness the day of is the best combo.
The best tornadoes always find a way to get going just before sunset.
Prepare yourself for what you may see. You may see a beautiful storm in an open field, you may see a violent tornado indiscriminately devastate anything in its path.
Phase 3: The Target
If you voice your opinion on how good a feeling you have today, it’s over.
Drive through morning convection.
Play the boundary.
Don’t “SPC Chase”. You picked your own target because you saw something they didn’t, right?
A 2% tornado risk with mention of “a brief tornado” means that if you go where the conditions are just right, you could have an absolutely awe-inspiring 20 minutes.
There will always be that one very specific Podunk town that always ends up being your target. Don’t question this.
Fast food chains have bad food but good WiFi.
You will realize that the MCS did ruin your forecast, but it sure laid down a nice boundary.
That single ob that holds a stubborn backed wind all day is not broken, it’s your target.
Who needs surface observations when every flying Star Spangled Banner rips north?
Roll the windows down and test the boundary. If it goes from a clammy 60 and rainy to a murky, sunny 85 in thirty minutes, you’re in the right place. If your camera lens fogs up, even better.
The “Morning Precip Tracer” Rule:
On an obvious tornadic day, one of the strongest / long-lived supercells will pass through the southernmost extent of morning precipitation, likely a result of synoptic forcing and surface boundary characteristics (definitely not a hard-and-fast rule).
Tornado = High 0-3km CAPE + High 0-1km SRH + Low LCL
Phase 4: The Wait
You goofed if you didn’t bring a Frisbee, but if you can throw it your southerlies aren’t good enough.
You picked your target for a reason. Stick with it.
Clouds give everything away:
- Misty? Moisture.
- High cu-fields? Instability upstairs.
- Low cu-fields? Instability downstairs.
- Cu’s leaning and torn instead of heaped? Speed shear.
- Cu’s aligned in rows? Directional shear.
- Cu’s with cap clouds? Very strong updrafts.
- A thin veil of cirrus? Just enough cap.
- Blue skies? Lots of cap.
- Low bases? Less distance a tornado needs to touch down.
Horizontal Convective Rolls point toward tornadoes; often very close to a boundary on its cool side, they signify strong shear and temporary stability. Stay near these.
- There will always be that one storm that forms earlier than the “main show”. It’s there to test how easily distracted you are.
- You know what kind of storm you’re after. Sure, storms are forming elsewhere, but are they the ones you want?
- Don’t let new SPC products change your thinking.
Perform the ceremonious tossing of the blades of grass.
If what you forecast just isn’t there yet, wait the extra hour for sunset when the low-level jet could still bring it all to life.
If storms are forming right on top of you, you’re doing it wrong. Be one step ahead.
Watch for blips.
Phase 5: The Pursuit
When thunder roars, go outdoors.
Top off on gas.
Lights on for safety.
Turn the GoPro to the “on” position.
Use “at 10 o’clock” instead of “straight ahead to the left a little behind the cows across from the cemetery”.
Picking the “Storm of the Day”:
This is highly variable and based off storm strength, longevity, and visual appearance:
- Forms where high 0-3km CAPE impinges on pool of high Eff. SRH with low LCLs
- Forms near a subtle boundary / triple point but not necessarily on it
- Forms ahead of remainder of storms
- Becomes southern “Tail-end Charlie” cell in a line
- Forms later than initial storms
- Forms more due to subtle synoptic forcing and less due to obvious surface feature
- Appears more defined/ragged in structure as opposed to murky/flat
- Ingests inflow region of clear skies/scattered cumulus as opposed to stratocumulus
- Possesses lengthy band of agitated cumulus feeding into inflow along storm motion
If you don’t have visual of your storm, use echo tops. If you do, the “nuclear” look will suffice.
If at any point a new updraft forms ahead of yours, that is your new storm.
Pick the “Storm of the Day”:
Watch for splitting storms. The non-dominant storm (possibly anti-cyclonic) will form to the north. These are beautiful, sculpted and scrawny as their low-level inflow is made stable by the rain from the dominant cell.
A thick, long inflow band means a powerful, long-lived updraft. Do all clouds seem to point towards the storm? It is now in control.
A sickle, banana or curved shape on radar means a rotating storm. Don’t wait for the hook.
Don’t let long-lived storms go unnoticed.
Approach from the East:
- If you tried from the North, you’re tempting fate.
- If you tried from the South, you’re about to play the game of catchup.
- If you tried from the West, you’re just going to have a bad time.
Yo ho, yo ho, through the hooks, I’ll never go.
Assume intercept position.
Phase 6: The Intercept
If you can see the rotation, you don’t need radar.
Eyes on the base.
If it’s not confirmed, confirm it.
Signs a tornado is imminent:
- Storm ingests a merger
- Inflow becomes strong
- Barrage of smooth-channel positive lightning strikes under wall cloud
- Base pushes to right of mean wind
- FFD inflow band or inflow tail becomes lower and ragged
- RFD shelf cloud becomes more well-built, surges forward
- RFD erodes wall cloud as it wraps around it
- FFD inflow tail tilts from horizontal to vertical
- Wall cloud is pushed back behind RFD shelf cloud, compacted
- Ragged tendrils of scud form and dance around
The “Bear’s Cage” is a lowering surrounded by bars of rain streaks that rotate around it. The “Bear” can and does grow as large as his cage.
Stop thinking of it as a wall cloud:
Rather, the dynamically changing intersection of the rear-flank downdraft and the forward-flank downdraft. The RFD is contained by a bowed shelf cloud surging forward. The FFD is often contained by an inflow band chugging into the storm. Follow the shelf cloud into the core. The northernmost tip, or where it intersects the inflow band, is where the RFD and FFD boundaries are pulled into tight rotation. If the base is lowest here, this is also the heart of the updraft. Once the RFD overtakes this area, however, the center of rotation occludes and is pushed back into the storm, while a new lowering forms ahead of it at the new intersection of the RFD and FFD. Low rising scud means you are looking at the heart of the updraft, but not always the heart of the rotation.
The angle between the RFD shelf and the FFD inflow band will tell you when a storm is wrapping up to produce a tornado. Near 180 degrees? Not yet. Near 90 degrees? It’s time.
The Horseshoe Base:
- A strong RFD will bow a supercell’s base into a horseshoe
- The cyclonic tornado will be at the northernmost tip
- The anticyclonic tornado (rare) will be at the southernmost tip
- Landspouts or gustnadoes can form anywhere in completely illogical places.
Smooth bases look sculpted because they are forced by the wind, with little natural rising motion from the surface. These rarely produce tornadoes.
Rough bases look ragged because they are rising from the surface. These may produce tornadoes.
Especially in slower storm motion environments, a supercell’s occluded mesocyclone may last for long periods of time alongside the newly-created forward mesocyclone:
- Forward mesocyclone: structurally more appealing, tornado less likely
- Rear mesocyclone: structurally less appealing, tornado more likely
- In when the updraft strengthens, temperatures rise, winds increase into the storm, the inflow band thickens, the wall cloud grows and lowers and lightning upticks.
- Out when the RFD surges forward, lightning quiets, the wall cloud gets pushed deeper into the storm as the updraft occludes and rotation speeds up.
Storms cycle; a new wall cloud may form ahead of the old, at the new intersection of the RFD and FFD.
Watch for double RFD structure. If the first RFD is too cold and stable to produce a tornado, a second, warmer RFD surge or occlusion downdraft may take over, adding buoyancy to the occluded rotation. Two RFD shelves may even be evident.
Don’t get swallowed; get out of the “Whale’s Mouth”.
Know the difference between corn-scraping scud and a tornado.
Mini-supercells are beautiful to watch from behind as tornadoes are almost never obscured and appear to form behind the storm.
- Don’t be that guy who, when you look at RadarScope and see a little red dot in the center of rotation, you think, “idiot…”
- Know what separates “people alive from people dead”.
- Easterly winds mean you are in danger.
- New development can pose great danger or yet another incredible experience.
Understand your tornado:
- Fast storms mean fast tornadoes.
- A well-defined, small area of rotation often means a well-defined, small tornado.
- A massive, low rotation with brief spin-ups often means a large, multi-vortex tornado.
- A trailing rear-inflow jet “ghost train” often means a strong tornado.
- Horizontal suction vortices often means a violent tornado.
- Rain-wrapping often strengthens a tornado before weakening it.
- A weak cell approaching a tornado often strengthens it.
- Roping out often means the end of a tornado.
- Tornadoes are often right-movers in the beginning and left (or even backwards)-movers in the end
- If you came to see a tornado, don’t act so surprised when it happens.
- Know that any adrenalized excitement may be at the expense of others’ lives.
- Never cheer, just watch and accept.
Phase 7: The Post-Chase
Be the first responder if no one responded first.
When bailing, the most obvious route is the one that likely just suffered heavy flash flooding, hail and wind damage and a tornado.
Turn around, don’t drown or get trapped in a flooded town.
Do not be a tourist.
Take a breather from reality and watch a stunning sunset or lightning display. Nature is cruel but always awe-inspiring. Never forget why you came; natural disasters cannot be prevented. It is difficult and painful to consider some days a success, but if you warned someone, helped someone, brought awareness to someone or learned anything that will help you do this in the future, you succeeded.
There is no such thing as a bust if you learned something.
Keep the driver awake.
Examine GoPro footage in the case that the entire team missed a blatantly obvious tornado.
Talk about what happened amongst your team. Everything from science to emotions.